Hydrodynamical winds from two-temperature plasma in X-ray binaries

Hydrodynamical winds from a spherical two-temperature plasma surrounding a compact object are constructed. The mass-loss rate is computed as a function of electron temperature, optical depth and luminosity of the sphere, the values of which can be constrained by the fitting of the spectral energy distributions for known X-ray binary systems. The sensitive dependence of the mass-loss rate with these parameters leads to the identification of two distinct regions in the parameter space separating wind-dominated from non-wind-dominated systems. A critical optical depth ( τ _c) is defined as a function of luminosity and electron temperature, which differentiates these two regions. Systems with optical depths significantly smaller than τ _c are wind-dominated.
The results are applied to black hole candidate X-ray binary systems in the hard spectral state (Cyg X-1, GX 339−4 and Nova Muscae), and it is found that the inferred optical depth ( τ ) is similar to τ _c, suggesting that they are wind-regulated systems. On the other hand, for X-ray binary systems containing a neutron star (e.g., Cyg X-2) τ is much larger than τ _c indicating the absence of significant hydrodynamical winds.     

Aftershocks of 26th january 2001 Bhuj earthquake and seismotectonics of the Kutch region

The 26th January 2001 Bhuj earthquake was followed by intense aftershock activity. Aftershock data from United States Geological Survey (USGS) utilized in this study encompasses three months period from 26th January to 26th April 2001. Epicenters of the aftershock are plotted on a map depicting active faults. All the aftershocks of magnitude > 5 and 70% of those ranging between magnitude 3 and 5 are confined to an area resembling a horseshoe pattern with a pointed end towards NE. The other 20% of magnitude 3 to 5 are enclosed within an almost parallel boundary. Only 10% are found to be beyond this limiting boundary. 50% of the recorded after-shocks took place within the first week of the main event and this study reveals that the basic characteristic pattern of aftershock activity can be determined on the basis of the data of only one week. Four major NW-SE trending active faults are mapped in the Kutch region. They define the western limit of Cambay structure and also mark the western limit of Dharangadhra and Wadhwan basins along the SE continuation in Saurashtra. These faults separate the Kutch region into two geologically different blocks. On the SW side the mapped horseshoe pattern gets characteristically truncated along the western most fault, which is characterized by a strike-slip movement in the south and vertical movement in the north. The present study has revealed that the epicenter of the 26th January earthquake is located in the vicinity of the Bhachau township, close to the intersection with the Kutch mainland fault. Furthermore, it has been noticed that most of the epicenters of the aftershock are confined in the intersectional area of the Kutch mainland fault and the NW-SE faults.     

Tropical-middle latitude interactions viewed via wave energy flux in the frequency domain

Over the upper troposphere of the polar latitudes the zonal flows exhibit a large variance on the time scale of the Madden-Julian oscillation, i.e. roughly 30–50 days. The other prominent regions for these intraseasonal oscillations are the Asian and Australian monsoon belts. These two regions are separated by the so-called critical latitude, to the south of which easterlies generally prevail and westerlies are prevalent to the north. A perplexing issue is that of possible tropical-middle latitude interactions across the critical latitude. The notion of the critical latitude emerged from the linear theories for the wave energy flux which assume a constancy in time for the zonal flows. This same problem, viewed in its full non-linear context, can be cast in a frequency domain. Such a formulation does not assume a constancy of the zonal flows in time but does permit the intraseasonal variations of the zonal flows to be present. The computation of the wave energy flux, from the more complete non-linear system in the frequency domain, requires the handling of linear, quadratic and triple product terms via use of Hayashi's co-spectral method. These results of the present study, based on 6 years of daily global data sets, show that wave energy flux clearly passes from the latitudes of the monsoon to the polar latitudes. A strong convergence of wave energy flux in the polar latitudes suggests the tropical-middle latitude convergence interactions across the so-called critical latitude—when the problem is viewed in the frequency domain.     

Determination of boundary-layer parameters using a vertical gill anemometer

The paper presents a simple method to compute the stability parameter Z/L and boundary-layer parameters such as friction velocity U ^* and surface heat flux Q ₀ on an operational basis. The method is based on the autocorrelation function of the vertical velocity which is relatively insensitive to averaging times except for very large lag times. Eddy correlation techniques on the other hand are very sensitive to averaging times.     

On the dispersion parameters of plumes from tall stacks in a shoreline environment

Experimental data for buoyant plumes released from high sources into layers having little ambient turbulence show that plume dispersion parameters vary in a manner similar to that during initial plume rise. This is consistent with general plume rise theory. Dispersion of plumes from tall stacks in a shoreline environment where a thermal internal boundary layer is formed often demonstrates this behaviour.     

Thermal stresses in a finite cylinder having temperature varying linearly along the length prescribed on the curved surface

Summary The problem of a finite cylinder of isotropic material in which the temperature on the curved surface varies linearly along its length and has its ends in contact with smooth rigid insulating plates has been investigated in this paper.     

Meteoritic Impacts and Climatic Changes in Pliocene–Pleistocene Epoch

During the Pliocene–Pleistocene epoch, covering last ∼5.2 Ma of Earth’s history, altogether 34 terrestrial meteoritic impact craters are known. Most of these craters (29) have diameter ≤10 km, among which 11 craters fall in 1,000 to 100 m range, and 7 are still smaller in dimension and of recent age. The age versus impact-frequency plot shows that the meteoritic impacts during this time period occurred in discrete intervals but have a periodicity that shows the best possible coincidence with the ∼425 Ky climatic cycles observed by Fourier analysis and FFT filtering of composite high resolution benthic foraminiferal δ¹⁸O record. This observation is also supported by Monte Carlo test with 71% success where meteoritic impact(s) shows coincidence with climatic cooling within our error limit. The newly observed climatic–meteoritic cycle may be same with the ∼400 Ky Milankovitch cycle or it is a different newly understood cycle relating both the climatic variation and meteoritic impact events.     

Sources of monazite sand in southern Orissa beach placer,eastern India

This paper intends to explore whether there is an important source for monazite beach placer of the Gopalpur-Chhatrapur-Rushikulya coast, Orissa, in the adjacent Eastern Ghat Mobile Belt (EGMB). Petrographic and mineralogical studies were conducted on all the rock types constituting the EGMB exposed over a stretch extended up to ∼20 km landward from the estuary of the River Rushikulya that is believed to transport the major bulk of sand to the Gopalpur-Chhatrapur-Rushikulya beach. Heavy mineral population was concentrated using bromoform and percentages of each heavy mineral constituting the population were estimated for all the potential source rock types. Isodynamic separation and XRD techniques were deployed for precision identification of every heavy mineral present. The study identified the granitoid (or migmatite) basement rock as by far the major contributor of monazite to the Chhatrapur beach sand. The study also reveals that charnockite is an important contributor of orthopyroxene as well as garnet, although the sillimanite-garnet-quartz schist (khondalites) is also an important source for the latter. On the other hand, garnet-quartz schist and garnet-biotite-quartz schist may also contribute substantial quantity of pyroxene and garnet. The high grade metasedimentary rocks, in general, could be the major sources for rutile, while ilmenite, magnetite and zircon in the beach sand have their sources perhaps in all the varieties of rocks constituting the EGMB.